Cut-out insulator for electric circuits



March 17, 1925. 1,530,201

J. N. ROBINSQN CUT-OUT INSULATOR FOR ELECTRIC CIRCUITS Filed Jan. 3, 1923 Patented Mar. 17, 1925.

UNITED STATES JOY IN NOBLE ROBINSON, OF HOKITIKA, NEW ZEALAND.

CUT-OUT INSULATOR FOR ELECTRIC CIRCUITS.

Application filed January 3, 1923. Serial No. 610,407.

To all whom it may concern Be it known that 1, JOHN Nonnn RomnsoN, subject of the King of Great Britain, residing at Hokitika, Dominion of New Zealand, have invented a new and useful Improvement in Cut-Out Insulators for Electric Circuits, of which the following is a specification.

My invention relates to that well known class of cut-out insulators used in electric circuits of arious kinds in which a body portion is provided and made with a recess in which terminals are fitted to connect with the circuit main ends, and a fuse carrier plug is provided to fit in such recess and to make electric contact between the said terminals through a fuse wire. This fuse wire then forms the safety fuse for controlling the circuit against overloading.

It has hitherto been proposed to construct these insulators in different ways according to the circumstances in which they are to be employed, either as switchboard attachments, pole insulators, or shackle and strain insulators for overhead work.

The present invention has been devised with the object of providing an insulator of this class that is specially adaptable for shackle or strain use and which construction is so designed that the insulator will be maintained well and firmly in its working position and so held that the fuse plug can be inserted and removed with a minimum of trouble and inconvenience and without any possibility of the operator being endangered by leakage of current, and by which construction also the insulator is made weather and watertight against the entry of rain and thereby the liability of short circuiting or leakage across between the terminals reduced to a minimum. The invention also consists in a particular arrangement and combination of the parts forming the insulater.

The construction devised is shown in the As shown, the insulator body is formed with a Hat base A rounded at its endsand grooved around the edge, as at B to permit of the wire lead C being secured around it in the usual way. At one end this base is .formed with an eye A (Fig. l.) extending vertically through it to receive the bolt of the shackle or other device by means of which the insulator is attached to the fixture upon which it is to be carried. At its other end, upon the top side, it is formed with a dome D enclosing a recess E on its underside that extends right down and opens through the bottom of the base in the form of a slot extending longitudinally. The sides of the dome D are formed of such a shape that they act to shed any water falling on the top thereof so that such water will be directed outward over the edges of the base and fall clear.

The bottom part of the recess formed at each end with a ledge E at a distance in from the under-surface of the base. On one of these ledges, a terminal block F is secured such block having spring contact fingers G combined therewith, and on the other ledgera similar block F, with contact lingers G, is secured. In both cases these spring contact lingers extend vertically downwardly. The lead C, (which in some cases may be the main lead and in others the branch lead) after passing round the base is carried in through an aperture made in the side of the body and secured to the terminal F, while the lead H (which also may be the main or the branch) is carried in through the other side of the body and secured to the terminal F, so that a bridging of the two terminals will complete the connection between the main and the branch.

The fuse plug is formed as a tongue piece J that is shaped to pass freely into the recess t, combined with a handle portion K and may have a flange M extending out all round the lower edge of the tongue. This flange is adapted to overlap the edge of the recess, an approved amount to provide for a weathertight cover being effected when the plug is placed in position. It also forms a protection for the fingers of an operator when handling the fuse plug and serves to divert any flame or molten metal resulting from a blow0ut when the plu is being inserted under overload cone itions. The tongueJ has secured to its sides, one on each side, the terminals N -N, each of which projects beyond its edge of the tongue, and both of which are so disposed that they will pass into the respective spring contacts G and G when the fuse plug is pushed into the recess, and will then be held firmly by the grip of such spring contacts. This gripping action will hold the fuse plug in position, but it may be removed at any time by means of an outward pull on the handle K, in the manner well known in the art.

The terminals l and N are connected together by the fuse wire 0 which passes from i one side of the tongue across the top to the other side, being retained in position by in the tongue top, as shown in Fig. 6.

The fuse plug is adapted to be fitted into the body to such an extent as to leave a marginal space all round for the escape of the flames and gases caused when the fuse wire fuses.

The insulator body and fuse plug are made of any of the approved materials employed in the construction of this class of appliance.

It will be apparent that the construction and arrangement of the parts forming the complete appliance will ensure of the insulator being held by its shackle or strain attachments to its supports, in a condition such as to maintain the upright position shown in the drawings, or positions approX- imate thereto. Consequently the fuse plug may be handled from beneath without any need of the operator coming into contact with the electric mains so that all liability of danger to the operator is entirely obviated. Moreover, the construction of the insulator ensures that the terminals and contacts are effectively protected against to immediately encircle the electric fittings of the insulator, and bring the fuse wire under the immediate influence of the leads, so that in the eventof the fuse wire fusing, or blowing out, under severe conditions, the magnetic field induced by the said lead winding, will serve to cause a quicker rupture of the arc and make the cut-out more positive in its action.

I claim An electric circuit out-out insulator, comprising a body portion shaped with a fiat base, having a wire holding groove extending round its edge to support therein one of the wires, and a shackle-attaching eye extending vertically throughout at one end, an arched dome being formed at the other end covering a recess provided to open upwards from the bottom of said base, a pair of spring contact terminals fitted in said recess, one near each end thereof, and a flanged fuse plug having a grooved tongue fitting said recess, and a handle extending from its bottom side, a pair of terminal pins affixed to said tongue, one on each side, and at opposite ends thereof, and so disposed as to respectively engage with the said two contact terminals, and a fuse wire connecting the said terminal pins and being retained in the groove of the said tongue.

In testimony whereof, I affix my signature.

JOHN NOBLE ROBINSON. 

